[BETA] The Sims 4 History Challenge (2.0)

I have a question regarding the marriage restrictions of each Era. Since the Early Civilisation Era begins when the Ancestors' grandchild is born, but marriage is forbidden as part of the Prehistoric Times Era, wouldn't the grandchild's birth violate the marriage restriction of the Early Civilisation Era as their parents weren't married when the Early Civilisation Era began?
In essence, when does the marriage restrictions rule begin? Does it apply to the Prehistoric Times parent the moment their child is born, or does it only apply to those born during the Early Civilisation Era? (I'm only using these two Eras as that's the farthest I've gotten.) In the former case, we've got a rule violation, in the latter case we've got a Prehistoric Times rule applying to Sims during the Early Civilisation.